The invention relates to a fan having an air guide and a fan wheel, the same being attached to a shaft, for the purpose of cooling an electric motor. The electric motor has a rotor which can be attached to the shaft. The air guide is arranged in an exchangeable manner at a position between the flywheel and the rotor with respect to the axial direction, and has an air guide opening with an inner cross section for the purpose of forming a blowing channel. An air flow which can be generated by the flywheel can be guided through the blowing channel in the axial direction. The invention also relates to an electric motor, having a stator and a rotor attached to a shaft, and having a fan with an air guide and with a flywheel attached to said shaft for the purpose of cooling the electric motor. The invention also relates to a machine tool having an electric motor, and to a method for the production of the electric motor.